Hybrid vehicles offer an opportunity for vehicle drivers to engage in environmentally-conscious behavior because of hybrids' improved fuel economy and reduced emissions. Hybrid vehicles combine traditional internal combustion engines with an electro-mechanical transmission. Electric motors located within the electro-mechanical transmission provide energy to propel the vehicle, reducing the need for energy provided by the internal combustion engine, thereby increasing fuel economy and reducing emissions.
As with any electric machine, the hybrid transmission's electric machine rejects some energy in the form of heat. Efficient removal of heat from the electric motor can improve the lifespan of the electric machine as well as improve the electric machine's operating efficiency.